IRS-P6 orbit determination and achieved accuracy during early phase

The IRS-P6 satellite launched by the Indian Space Research Organization (ISRO) is envisaged as a continuity mission of ISRO's earlier spacecraft IRS-1C and IRS-1D, with enhanced capabilities both in the platform and payloads. The orbit determination results for all the Indian Remote Sensing (IRS) satellites of ISRO are obtained by the operational orbit determination software “ISRO-ODP” developed at ISRO Satellite Centre using a batch least squares estimator to process S-band range and range rate measurements. This paper describes the IRS operational orbit determination system and its performance during the initial phase of the mission, and it also highlights the achieved orbit determination accuracy based on two different methods: (1) “difference in position” method, and (2) by presenting the results of an experiment which was designed to ascertain the level of agreement between the ISRO-ODP results and the orbit solutions obtained using tracking data from Global Positioning System.